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Synthesis of an oligo(phenylenevinylene)-bridged phthalocyanine dimer
Synthetic Metals 111–112 Ž2000. 453–454 www.elsevier.comrlocatersynmet
Synthesis of an oligo žphenylenevinylene/ -bridged phthalocyanine dimer Reiner Jung, Karl-Heinz Schweikart, Michael Hanack ) Institut fur Auf der Morgenstelle 18, D-72076 Tubingen, Germany ¨ Organische Chemie, Lehrstuhl II, UniÕersitat ¨ Tubingen, ¨ ¨
Abstract As a model compound for corresponding PPV polymers containing phthalocyanine ŽPc. subunits a phenylenevinylene-bridged nickel Pc dimer is synthesized. The synthesis route includes a modified Pc-monoaldehyde, which furnishes with 0.5 equivalents of p-xylylene bisŽtriphenylphosphonium.bromide in a Wittig reaction the Pc dimer. q 2000 Elsevier Science S.A. All rights reserved. Keywords: Unsymmetrical phthalocyanines; Wittig reactions
1. Introduction Recently, great efforts have been devoted to introduce macrocyclic moieties into the backbone of conjugated polymers, because macromolecular chromophoric structures like porphyrines and phthalocyanines ŽPcs. exhibit remarkable electrical and optical properties and high stabilities w1x. Pc subunits are expected to improve the properties of a resulting phthalocyanine-PPV ŽPcPPV., especially the stability. Moreover, the absorption spectra of Pcs show two major absorption bands at around 340 and 650 nm. Therefore, a PcPPV is expected to have an increased absorption range compared to PPV Ž402 nm. w2x. This characteristic, the stability, and high absorption coefficients of Pcs make PcPPV particularly interesting for applications, e.g., in high-efficiency solar cells w3x. Pcs are nearly transparent where electroluminescent ŽEL. emissions of PPV Ž520 and 551 nm. occur but are expected to alter the electrical behaviour. This is advantageous for applications in organic light emitting diodes ŽOLEDs., where Pcs are still employed as hole-transporting or contact-modifying layers in multistructure devices
)
Corresponding author. Fax: q49-7071-295244. E-mail address: [email protected] www.uni-tuebingen.der hanackrindex.html ŽM. Hanack..
w4x. Here, we report on a dimeric structure model compound as the first step for the preparation of a PcPPV.
2. Results and discussion In Scheme 1 the synthesis of the novel PcPPV model compound is shown. For the preparation of 1, a method is described in our works on unsymmetrically substituted Pcs Žby reacting an unsymmetrical monodienophilic Pc with 1,2,3,4-tetraphenyl cyclopentadienone Žtetracyclone.. w5,6x. Compound 1 is a precursor to a reactive isobenzofuran derivative, which is formed in situ by loss of CO and 1,2,3,4-tetraphenylbenzene ŽTPB. when heated, for example in refluxing toluene. Diels–Alder reaction with acrolein Ž2. in an autoclave at 1408C resulted in the corresponding acrolein-adduct 3. An excess of acrolein was used to act as both reactant and solvent. Dehydration of 3 can be accomplished by reacting it with a six-fold excess of p-toluenesulfonic acid in toluene at 808C to give the modified Pc-monoaldehyde 4. Reaction of 4 with 0.5 equivalents of p-xylylene bisŽtriphenylphosphonium.bromide 5 in dry THF at room temperature furnished the oligoŽphenylenevinylene.-bridged dimer 6, using potassium tert-butylate as base. The UV–VIS data of the new Pc derivatives 3, 4 and 6 are listed in Table 1 Žrecorded in CH 2 Cl 2 solution.. The synthesis of 7 represents a first step towards the preparation of a PcPPV containing Pc subunits either end-on attached or within the polymer backbone. Work on
0379-6779r00r$ - see front matter q 2000 Elsevier Science S.A. All rights reserved. PII: S 0 3 7 9 - 6 7 7 9 Ž 9 9 . 0 0 3 9 8 - 7
R. Jung et al.r Synthetic Metals 111–112 (2000) 453–454
454
Scheme 1. Synthesis of Pc dimer 6.
the synthesis of this type of compounds is presently underway. Table 1 UV–VIS absorption peaks Žin nm. of compounds 3, 4 and 6 Compound
3
4
6
UV–VIS wnmx
668, 602, 392, 308
692, 632 393, 331
693, 648 388, 328
References w1x C.C. Leznoff, A.B.P. Lever ŽEds.., Phthalocyanines, Properties and Applications 1–4 VCH, New York, 1989–1996. w2x J. Obrzut, F.E. Karasz, J. Chem. Phys. 87 Ž1987. 6178. w3x D. Wohrle, D. Meissner, Adv. Mater. 3 Ž1991. 129. ¨ w4x S.A. Van Slyke, C.H. Chen, C.W. Tang, Appl. Phys. Lett. 69 Ž1996. 2160. w5x P. Stihler, B. Hauschel, M. Hanack, Chem. Ber. 130 Ž1997. 801. w6x T.G. Linßen, M. Hanack, Chem. Ber. 127 Ž1994. 2051.
Synthesis of an oligo žphenylenevinylene/ -bridged phthalocyanine dimer Reiner Jung, Karl-Heinz Schweikart, Michael Hanack ) Institut fur Auf der Morgenstelle 18, D-72076 Tubingen, Germany ¨ Organische Chemie, Lehrstuhl II, UniÕersitat ¨ Tubingen, ¨ ¨
Abstract As a model compound for corresponding PPV polymers containing phthalocyanine ŽPc. subunits a phenylenevinylene-bridged nickel Pc dimer is synthesized. The synthesis route includes a modified Pc-monoaldehyde, which furnishes with 0.5 equivalents of p-xylylene bisŽtriphenylphosphonium.bromide in a Wittig reaction the Pc dimer. q 2000 Elsevier Science S.A. All rights reserved. Keywords: Unsymmetrical phthalocyanines; Wittig reactions
1. Introduction Recently, great efforts have been devoted to introduce macrocyclic moieties into the backbone of conjugated polymers, because macromolecular chromophoric structures like porphyrines and phthalocyanines ŽPcs. exhibit remarkable electrical and optical properties and high stabilities w1x. Pc subunits are expected to improve the properties of a resulting phthalocyanine-PPV ŽPcPPV., especially the stability. Moreover, the absorption spectra of Pcs show two major absorption bands at around 340 and 650 nm. Therefore, a PcPPV is expected to have an increased absorption range compared to PPV Ž402 nm. w2x. This characteristic, the stability, and high absorption coefficients of Pcs make PcPPV particularly interesting for applications, e.g., in high-efficiency solar cells w3x. Pcs are nearly transparent where electroluminescent ŽEL. emissions of PPV Ž520 and 551 nm. occur but are expected to alter the electrical behaviour. This is advantageous for applications in organic light emitting diodes ŽOLEDs., where Pcs are still employed as hole-transporting or contact-modifying layers in multistructure devices
)
Corresponding author. Fax: q49-7071-295244. E-mail address: [email protected] www.uni-tuebingen.der hanackrindex.html ŽM. Hanack..
w4x. Here, we report on a dimeric structure model compound as the first step for the preparation of a PcPPV.
2. Results and discussion In Scheme 1 the synthesis of the novel PcPPV model compound is shown. For the preparation of 1, a method is described in our works on unsymmetrically substituted Pcs Žby reacting an unsymmetrical monodienophilic Pc with 1,2,3,4-tetraphenyl cyclopentadienone Žtetracyclone.. w5,6x. Compound 1 is a precursor to a reactive isobenzofuran derivative, which is formed in situ by loss of CO and 1,2,3,4-tetraphenylbenzene ŽTPB. when heated, for example in refluxing toluene. Diels–Alder reaction with acrolein Ž2. in an autoclave at 1408C resulted in the corresponding acrolein-adduct 3. An excess of acrolein was used to act as both reactant and solvent. Dehydration of 3 can be accomplished by reacting it with a six-fold excess of p-toluenesulfonic acid in toluene at 808C to give the modified Pc-monoaldehyde 4. Reaction of 4 with 0.5 equivalents of p-xylylene bisŽtriphenylphosphonium.bromide 5 in dry THF at room temperature furnished the oligoŽphenylenevinylene.-bridged dimer 6, using potassium tert-butylate as base. The UV–VIS data of the new Pc derivatives 3, 4 and 6 are listed in Table 1 Žrecorded in CH 2 Cl 2 solution.. The synthesis of 7 represents a first step towards the preparation of a PcPPV containing Pc subunits either end-on attached or within the polymer backbone. Work on
0379-6779r00r$ - see front matter q 2000 Elsevier Science S.A. All rights reserved. PII: S 0 3 7 9 - 6 7 7 9 Ž 9 9 . 0 0 3 9 8 - 7
R. Jung et al.r Synthetic Metals 111–112 (2000) 453–454
454
Scheme 1. Synthesis of Pc dimer 6.
the synthesis of this type of compounds is presently underway. Table 1 UV–VIS absorption peaks Žin nm. of compounds 3, 4 and 6 Compound
3
4
6
UV–VIS wnmx
668, 602, 392, 308
692, 632 393, 331
693, 648 388, 328
References w1x C.C. Leznoff, A.B.P. Lever ŽEds.., Phthalocyanines, Properties and Applications 1–4 VCH, New York, 1989–1996. w2x J. Obrzut, F.E. Karasz, J. Chem. Phys. 87 Ž1987. 6178. w3x D. Wohrle, D. Meissner, Adv. Mater. 3 Ž1991. 129. ¨ w4x S.A. Van Slyke, C.H. Chen, C.W. Tang, Appl. Phys. Lett. 69 Ž1996. 2160. w5x P. Stihler, B. Hauschel, M. Hanack, Chem. Ber. 130 Ž1997. 801. w6x T.G. Linßen, M. Hanack, Chem. Ber. 127 Ž1994. 2051.